TESTS have found 21 bottles of “rare Scotch whisky” thought to be worth around £635,000 are modern fakes.

The results, from more than nine months of testing, indicate the problem involving high-value spirits in the secondary market is much more prevalent than originally thought.

Individual bottles could have fetched anything from £2,500 for the lowest value right up to an estimated £150,000.

Rare Whisky 101 has estimated that around £41 million worth of the fake spirits are currently circulating in the secondary market.

Co-founder David Robertson said: “We are clearly disappointed to discover that, without exception, every single ‘antique’ pre-1900 distilled whisky RW101 have had analysed over the last two years has proven to be fake.

“It is our genuine belief that every purported pre-1900 – and in many cases much later – bottle should be assumed fake until proven genuine, certainly if the bottle claims to be a single malt Scotch whisky.

“This problem will only grow as prices for rare bottles continue to increase.”

Three bottles of rare whisky acquired through different channels were of particular note.

These were an Ardbeg 1885 acquired from a private owner, a bottle of rare Thorne’s Heritage early 20th century blended whisky purchased from an auctioneer, and a bottle of Ardbeg purported to be bottled in the 1960s bought from a retailer.

All three were proven to be fakes.

Tests were carried out at the Scottish Universities Environmental Research Centre (SUERC) which identified levels of radiocarbon.

Professor Gordon Cook, head of the SUERC radiocarbon laboratory, said: “We have had significant help from the major distillers who provided whisky samples of known age that allowed us to start this work.

“It is disappointing to see the large percentage of vintage whiskies that turn out to be fake.

“However, we have developed a very powerful technique to beat the fraudsters and I’d advise anyone thinking about selling what they consider to be an early product to have it analysed.”